The clinical efficacy of three indigenous plants was compared with that of ampicillin and placebo in a randomized double blind clinical trial. Eighty-two men with shigellosis were studied. Sixteen patients received dried unripe fruit powder of 'bel' (Aegle marmelos), 19 received dried powdered plant of 'thankuni' (Hydrocotyle asiatica), 15 received a similar preparation of 'gandhavadulia' (Paederia foetida), 15 received ampicillin and 17 received a placebo. Treatment with indigenous plants did not show any clinical improvement or bacteriological cure as compared to ampicillin. The natural history of shigellosis was obtained by documenting the response of the indigenous plants and placebo treated groups.